The Damian Green affair has become muddled by anger and outrage. Several distinct strands about the position of civil servants and MPs need to be disentangled.

First, Christopher Galley, the self-confessed leaker, has unquestionably breached the Civil Service code and the ties of loyalty and trust that apply in any large organisation. There is no right to pass information to an opposition MP, even if you are worried about how your department is being run. Complaints procedures, including appeals up to the Civil Service Commissioners, exist to deal with such concerns. But even breaches of the code need not involve a criminal inquiry as opposed to a disciplinary one. Secondly, there is a long tradition of whistleblowing in which information about alleged executive wrongdoing is sent to MPs and journalists. Often, this is passive and anonymous and there is no question of prosecution. But did Mr Green encourage Mr Galley’s leaking in any way? That is what so concerns the Government. The Tories strongly deny that any inducements were offered and Mr Galley was turned down for a job with them. However, Mr Green and he did talk.

Thirdly, and contrary to many furious comments since last week, parliamentary privilege applies only to what is said and does not give MPs or their offices within the Palace of Westminster any special protection from the law and police inquiries.

The question is more one of judgment. MPs have a special, if not always privileged, position that depends on confidential relations with constituents and others. There has to be a very tall hurdle before an MP is arrested and his offices and home searched. There should be evidence of a serious crime. But there has been no allegation that Mr Green risked national security.

The police behaved in a heavy-handed manner, out of all proportion to the gravity of what happened. At the very least there should have been consultations about the implications. The police cannot ignore the special position of Parliament. This need not compromise their operational independence. But the Chief Inspector of Constabulary exists to be a sounding board for the Home Secretary and chief constables in such cases.

Similarly, Michael Martin, the Commons Speaker, has a lot to explain today. He needs to clarify what talks he had with the police; and whether he sought legal advice. This is a matter of Parliament’s standing as much as of privilege. Mr Martin should allow MPs full scope to express their fury. But outrage should not be one-sided. It should recognise not just the rights of MPs but also the duties of civil servants.

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